Network polymer systems

Spatial Inhomogeneity of Cavities in Polymer Network Systems as Characterised by Field-Gradient NMR Using Probe Diffusant Molecules and Polymers with Different Sizes... 

Spatial Inhomogeneity of Cavities in Polymer Network Systems... 

A modification of the oriented polymer network systems are polymer stabilized liquid crystals (PSLC) 4) being studied in detail because of their application in flat-panel displays. In these materials, photopolymerizable diacrylate monomers are usually dissolved at a concentration less than 10% in non-reactive low-molar-mass liquid crystal solvents, commonly available, along with a small concentration of photoinitiator. Typically, the addition of small amounts of monomers and photoinitiator reduces the transition temperatures of the pure low-molar-mass liquid crystals slightly, suggesting that the order in the system is not dramatically altered by the addition of monomers or initiator. In application, this solution is aligned in a particular desired state and then photopolymerized. Photopolymerization is preferred to thermal free-radical polymerization, because photopolymerizations are very fast and because the temperature of photopolymerization can be controlled more easily to optimize processing of the display. 

Fig. 11. Automotive finishes such as that on the Honda Civic have depth, luster and environmental resistance that is the result of a complex mixture of hybrid organic-inorganic materials cured into mixed graft interpenetrating polymer network systems.

Interpenetrating networks. These are composite materials that are often used in polymer technology to circumvent the frequently encountered problem that modifications that enhance a desired performance parameter (e.g. conductivity) often do so at the expense of mechanical properties. One polymer network system provides the matrix for the required process and mechanical stability is conferred by the other. 

In a study on an AB polymer network system with triple-shape capability, the influence of the programming and recovery process on the crystalline domains was investigated by means of WAXS and SAXS experiments [24,25]. The triple-shape capability obtained by a one-step triple-shape creation process, similar to a conventional dual-shape programming process, was reported for networks based on PCL and PCHMA. Favorable compositions for obtaining a triple-shape effect contained... 

The creation of the triple-shape capability for an AB polymer network system by a simple one-step process similar to a conventional dual-shape progranuning process was shown for networks based on PCL and PCHMA [24] (see Sect. 2.4). In these materials a stress-controlled cyclic, thermomechanical experiment was used to quantify the triple-shape effect. The sample was deformed at 150°C (liigh) to 50% (Ein) and subsequently cooled to —10°C (Tio ). The large temperature interval of around 160 K led to a strong reduction of the strain. When the sample was heated... 

Zh. D. Chernova, K. Kalnins, and G. P. Belonovskaya, IR-Spectroscopic Study of Some Kinetic Characteristics of the Formation of Interpenetrating Polymer Network Systems, Vysokomol. Soedin. Ser. B 19(1) 61 (1977). IPNs of TDI/polypropylene sulfide. 

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